This invention relates to optical sheet material and, more specifically, to such sheet material characterized by bulk diffusion of light.
In backlight computer displays or other display systems, optical films or sheet material are commonly used to direct, diffuse or polarize light. For example, in backlight displays, brightness enhancement films use prismatic structures on the surfaces thereof to direct light along a viewing axis (i.e., an axis normal to the display). This enhances the brightness of the light viewed by the user of the display and allows the system to consume less power in creating a desired level of on-axis illumination. Such films can also be used in a wide range of other optical designs, such as in projection displays, traffic signals, and illuminated signs.
In current displays systems, for example in Liquid Crystal Displays (LCD), it is desirable to have diffusing components. Examples of the utility of diffusing components include (but are not limited to) masking artifacts, such as seeing electronic components located behind the diffuser film, improved uniformity in illumination and increased viewing angle. In a typical LCD display, diffusion of light is introduced into the backlight assembly by adding separate films (i.e., a stack) that are comprised of a non-diffusing substrate to which a highly irregular, diffusing surface treatment is applied or attached. It is thus desirable to generate diffuse light with out the added cost of separate films.